Manufacture of wrought iron



Patented Sept. 13, 1938 UNlTED STATES PATENT OFFICE Best, Edgeworth, Pa.,

assignors to A. M. Byers Company, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application January 19, 1938, Serial No. 185,704

7 Claims.

This invention relates to the manufacture of wrought iron, and more particularly to the manufacture of wrought iron by the now well known Aston process in which molten ferrous material .5 is admixed with molten slag to form a wrought iron sponge ball. This application is in part a continuation of our copending application Serial No. 133,808, filed March 30, 1937.

It has long been recognized that the tempera- 10 ture relationship between the molten ferrous material and the molten slag must be controlled within certain fairly well defined limits in order that the best results may be obtained. However, the effecting of the desired temperature control has presentd certain difliculties which prior to the present invention have not been overcome with entire success.

In the modern Aston process as carried out at the Ambridge plant of A. M. Byers Company molten ferrous material is admixed with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball so that there is formed a sponge ball with an excess of molten slag. The excess slag is separated from the ball and is reused in the formation of subsequent balls, being replenished from time to time as necessary with additional molten slag. The balls now being made normally range in size from two to eight tons, and the cycle of operations is carried out much faster than heretofore. Certain improved methods of procedure and apparatus bringing about materially increased speed of operation are disclosed and claimed in our copending application Serial No. 133,809, filed March 30, 1937. Such application relates primarily to certain manipulative steps in the Aston process, particularly with reference to the handling of the slag receptacles.

The practice of replenishing with molten slag, -40 the increased size of the balls formed and the increase in the speed of operation have rendered increasingly difiicult the problem of temperature control. All of the factors mentioned tend to undesirably increase the temperature of the slag,

45 and on many occasions great difiiculty has been experienced in keeping the slag temperature sufficiently low to insure a proper disintegration of the molten ferrous material. It is well recognized that when the slag temperature becomes too great the molten ferrous material'will not properly disintegrate and a ball of low or non-uniform quality will result.

In the early days of the Aston process when comparatively small sized balls were produced at comparatively slow speed without replenishment of the excess slag with molten slag it was proposed to introduce cold pulverized slag into the slag receptacle during the processing operation to keep down the temperature of the slag bath. However, this did not prove satisfactory, the cold 5 pulverized slag interfering with proper disintegration of the metal. Other expedients for keeping down the slag temperature were resorted to, as, for example, the use of a plurality of slag receptacles in which the processing operation is 1 carried on more or less simultaneously, resulting in a considerable time lag during the cycle, particularly while the excess slag is being decanted and the ball dumped. Such method obtains good temperature control but greatly im-*'; 5 pairs the efiiciency of the operation.

We have discovered that under present day conditions as above described proper slag temperature control can be effected by introducing into the slag receptacle after completion of the proc- 20 cessing operation a quantity of relatively cold solidified slag. In this way We are able to reduce the slag temperature without interfering with proper disintegration of the ferrous material during processing. In other words, the temperature control is effected in advance of the succeeding processing operation in which the temperature control is felt. The cold solidified slag which is introduced has an opportunity to melt and homogenize with the molten slag in advance of the processing operation so that simply by control of the quantity of solidified slag introduced substantially ideal conditions of operation may be produced with virtual certainty.

' The cold solidified slag is introduced in substantial quantities, the exact quantity depending upon the mass and temperature of the slag and the temperature reduction desired. Up to 200 or 300 pounds of cold solidified slag may be introduced at each cycle when balls of the sizes 40 above mentioned are being formed. Up to 600 pounds of cold solidified slag has been introduced intermediate successive processing operations with desired results. In the course of a days time the amount of cold solidified slag thus introduced mounts up greatly and may, for example, total in the neighborhood of 25 to 30 tons per day or even more. The economy of the process is thus further increased, as no external heat need be applied to melt this substantial r quantity of slag. Thus despite conditions which are unfavorable for temperature control we are able at thesame time to control the slag temperature and increase the efficiency of the plant.

The process is preferably carried out by providing a receptacle of molten slag at proper temperature and pouring into the slag bath molten ferrous material of characteristics suitable for the manufacture of wrought iron, as well known. The ferrous material disintegrates in the slag bath and builds up on the bottom of the receptacle the well known wrought iron sponge ball. An excess of slag-is used so that after formation of the ball there remains in the receptacle with the ball a quantity of excess molten slag whose temperature has been raised by the molten ferrous material.

We find it preferable to introduce the cold solidified slag after completion of the pouring or processing step and before separating the ball and excess slag. It is convenient to introduce the cold solidified slag into the receptacle while it is still at the processing station immediately after completion of the pour. Thus the cold solidified slag is introduced into the bath of molten slag when the bath is at substantially its highest temperature but after formation of the sponge ball has been completed so that there will be no possibility of any of the relatively cold slag getting into the sponge ball before such slag is completely melted and has had an opportunity to homogenize with the remainder of the molten slag. Thereafter the excess slag, including the slag introduced after processing, is separated from the ball, the preferred method of effecting such separation being by decanting off the slag. The decanting assists in mixing and homogenizing the slag and thus aids in rapidly melting the cold solidified slag. If the receptacle containing the decanted slag is returned directly to the processing station the slag will have sufficiently homogenized by the time the succeeding processing operation is commenced to enable obtaining of the desired results.

In the modern, high speed Aston process as above described the quantity of cold solidified slag introduced intermediate processing operations is generally such that it does not all reach the molten state during its passage downwardly through the molten slag in the receptacle. The wrought iron sponge ball forms on the bottom of the receptacle and when the cold solidified slag is introduced such slag, being heavier than the molten slag, tends to gravitate through the molten slag and a considerable proportion of it settles in non-molten condition in proximity to the ball. Generally at least a substantial part of such relatively cold slag forms as a crust on the ball. The non-molten slag which settles on or in proximity to the ball absorbs heat from the ball which raises the temperature of such slag toward the melting temperature. When the excess slag is separated from the ball this non-molten or partially molten slag stays with the molten slag, and this is true even though a crust has formed on the wrought iron ball. If the separation is effected by decanting, which is preferred, the non-molten or partially molten slag and/ or crust separates from the ball and flows off with the decanted molten slag. The agitation of the slag in the separating step, and particularly when separation is effected by decanting, serves to thoroughly commingle the molten slag and the non-molten or partially molten slag, and, especially as the latter has absorbed considerable heat from the ball prior to separation of the ball and slag, it quickly becomes molten, rendering the slag bath suitable for formation of the succeeding ball. The combined effect of the absorption of heat from the ball by slag introduced as cold solidified slag and the agitation of the slag in the separating step is to melt such introduced slag prior to the succeeding ballforming operation. Ordinarily the time interval between the introduction of the cold solidified slag and the separation of the ball and the slag in the receptacle not incorporated in the ball is of the order of one minute, and in this time the introduced slag has time to absorb sufficient heat from the ball so that after the agitation occurring in the decanting or other separating step and the further time interval prior to the succeeding processing operation the bath will have become entirely molten.

Ordinarily replenishment with additional molten slag is not effected during each cycle of operation. It may be effected, for example, every third or fourth cycle. When replenishment is effected the additional molten slag may be introduced either before, during or after separation of the ball and excess slag. Generally it is found most convenient to replenish after separation, that is, in the present day operation of the Ambridge plant, after the excess slag has been decanted from the receptacle containing the ball into another receptacle. Thus if the cold solidified slag is added after decanting but before replenishment with molten slag the introduction of the replenishing slag assists in melting and homogenizing the slag added as cold solidified slag. The amount of cold solidified slag which is added to obtain the desired temperature control is much less than the amount needed for replenishment to maintain the necessary slag volume and it does .not take the place of replenshment with molten slag. Rather, the two go hand-in-hand in effecting the desired control of both slag volume and slag temperature.

As indicated above, the slag added as cold solidified slag normally should be admixed with the molten slag before the succeeding processing operation. This is particularly true in high speed operation. If the time lag is sufliciently great the solidified slag may sufiiciently melt and homogenize with the molten slag without any admixture other than that caused by introduction of the solidified slag into the bath of molten slag, but it is preferable to aid in bringing this about by agitating the slag bath, as, for example, by introducing molten slag for replenishment after introduction of the cold solidified slag or by decanting the slag bath from one receptacle into another. This is one of the reasons why it is preferable to introduce the cold solidified slag into the slag receptacle before separating the excess slag from the ball formed in the preceding processing operation. We have obtained excellent results in actual commercial operation by this method of temperature control.

While we have described certain present preferred methods of carrying out our invention, it is to be distinctly understood that the same is not limited thereto but may be otherwise variously practiced within the scope of the following claims.

We claim:

1. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufficient to form with.the ferrous material a Wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle such an amount of relatively cold solidified slag that such relatively cold solidified slag does not all reach molten state during its passage downwardly through the molten slag in the receptacle, thereafter separating the ball and the slag in the receptacle not incorporated in the ball and during such separation agitating such slag to promote melting of such of said relatively cold solidified slag as had not theretofore reached molten state, and thereafter utilizing such slag not incorporated in the ball as at least a part of a quantity of molten slag for admixture with ferrous material to form another Wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

2. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufficient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle a quantity of relatively cold solidified slag, thereafter, and before such relatively cold solidified slag has all reached molten state, separating the ball and the slag in the receptacle not incorporated in the ball and during such separation agitating such slag to promote melting of such of said relatively cold solidified slag as had not therefore reached molten state, and thereafter utilizing such slag not incorporated in the ball as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

3. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle such an amount of relatively cold solidified slag that at least a portion thereof forms. a crust of nonmolten slag on the outer surface of the ball and absorbs heat from the ball which raises the temperature of the crust toward melting temperature, thereafter separating the ball and the slag in the receptacle not incorporated in the ball including such crust and during such separation agitating such slag to promote melting of such crust, and thereafter utilizing such slag not incorporated in the ball as at least a part of a quantity of molten slag for admixture with ferrous material to form another Wrought iron sponge ball and admixing molten ferrous mate-,

rial with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

4. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle such an amount of relatively cold solidified slag that at least a portion thereof forms a crust of nonmolten slag on the outer surface of the ball and absorbs heat from the ball which raises the temperature of the crust toward melting temperature, thereafter decanting into another receptacle the crust from the ball and agitating the decanted slag to promote'melting of the crust, and thereafter utilizing the decanted slag as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form'said second mentioned wrought ironsponge ball.

5. In themanufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle such an amount of relatively cold solidified slag that such relatively cold solidified slag does not all reach molten state during its passage downwardly through the molten slag in the receptacle, at least a substantial proportion of such introduced slag settling in non-molten condition in proximity to the ball and absorbing heat from the ball which raises its temperature toward melting temperature, thereafter separating the ball and the slag in the receptacle not incorporated in the ball and during such separation agitating such slag to promote melting of such of said introduced slag as had not theretofore reached molten state, and thereafter utilizing such slag not incorporated in the ball as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

6. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball and thereby forming a Wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptacle such an amount of relatively cold solidified slag that such relatively cold solidified slag does not all reach molten state during its passage downwardly through the molten slag in the receptacle, at least a substantial proportion of such introduced slag settling in non-molten condition in proximity to the ball and absorbing heat from the ball which raises its temperature toward melting temperature, thereafter decanting into another receptacle the slag in the first mentioned receptacle not incorporated in the ball including said settled slag while retaining the ball in the first mentioned receptacle, such decanting agitating and thereby tending to commingle the molten and non-molt'en components of the decanted slag and thus promoting melting of the non-molten slag, and thereafter utilizing the decanted slag as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned Wrought iron sponge ball.

7. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufiicient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, thereafter introducing into the receptaclesuch an amount of relatively cold solidified slag that such relatively cold solidified slag does not all reach molten state during its passage downwardly through the molten slag in the receptacle, thereafter separating the ball and the slag in the receptacle not incorporated in the ball and during such separation agitating such slag to promote melting of such of said relatively cold solidi- CERTIFICATE OF CORRECTION.

j Patent No, 2,129,718, September 15, 1958.

EDWARD B. STORY, ET AL.

.[t is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page .1, second column, line 1h, for "tall" read balls; and page5, first column, line 28,

claim 2, for the wor d therefore" read theretofore; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Officeo Signed and sealed this 25th day of October, A. D. 1958.

Henry Van Arsdale (Seal) Acting Commissioner of Patents, I 

